/**
 * Copyright (C) 2011 Whisper Systems
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.appspot.eusms.database;

import android.content.Context;
import android.os.Environment;
import android.util.Log;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.channels.FileChannel;

public class EncryptedBackupExporter {

    public static void exportToSd(Context context) throws NoExternalStorageException, IOException {
        verifyExternalStorageForExport();
        exportDirectory(context, "");
    }

    public static void importFromSd(Context context) throws NoExternalStorageException, IOException {
        verifyExternalStorageForImport();
        importDirectory(context, "");
    }

    private static String getExportDirectoryPath() {
        File sdDirectory = Environment.getExternalStorageDirectory();
        return sdDirectory.getAbsolutePath() + File.separator + "TextSecureExport";
    }

    private static void verifyExternalStorageForExport() throws NoExternalStorageException {
        if (!Environment.getExternalStorageDirectory().canWrite())
            throw new NoExternalStorageException();

        String exportDirectoryPath = getExportDirectoryPath();
        File exportDirectory = new File(exportDirectoryPath);

        if (!exportDirectory.exists())
            exportDirectory.mkdir();
    }

    private static void verifyExternalStorageForImport() throws NoExternalStorageException {
        if (!Environment.getExternalStorageDirectory().canRead() ||
                !(new File(getExportDirectoryPath()).exists()))
            throw new NoExternalStorageException();
    }

    private static void migrateFile(File from, File to) {
        try {
            if (from.exists()) {
                FileChannel source = new FileInputStream(from).getChannel();
                FileChannel destination = new FileOutputStream(to).getChannel();

                destination.transferFrom(source, 0, source.size());
                source.close();
                destination.close();
            }
        } catch (IOException ioe) {
            Log.w("EncryptedBackupExporter", ioe);
        }
    }

    private static void exportDirectory(Context context, String directoryName) throws IOException {
        File directory = new File(context.getFilesDir().getParent() + File.separatorChar + directoryName);
        File exportDirectory = new File(getExportDirectoryPath() + File.separatorChar + directoryName);

        if (directory.exists()) {
            exportDirectory.mkdirs();

            File[] contents = directory.listFiles();

            for (int i = 0; i < contents.length; i++) {
                File localFile = contents[i];

                if (localFile.isFile()) {
                    File exportedFile = new File(exportDirectory.getAbsolutePath() + File.separator + localFile.getName());
                    migrateFile(localFile, exportedFile);
                } else {
                    exportDirectory(context, directoryName + File.separator + localFile.getName());
                }
            }
        } else {
            Log.w("EncryptedBackupExporter", "Could not find directory: " + directory.getAbsolutePath());
        }
    }

    private static void importDirectory(Context context, String directoryName) throws IOException {
        File directory = new File(getExportDirectoryPath() + File.separator + directoryName);
        File importDirectory = new File(context.getFilesDir().getParent() + File.separator + directoryName);

        if (directory.exists() && directory.isDirectory()) {
            importDirectory.mkdirs();

            File[] contents = directory.listFiles();

            for (File exportedFile : contents) {
                if (exportedFile.isFile()) {
                    File localFile = new File(importDirectory.getAbsolutePath() + File.separator + exportedFile.getName());
                    migrateFile(exportedFile, localFile);
                } else if (exportedFile.isDirectory()) {
                    importDirectory(context, directoryName + File.separator + exportedFile.getName());
                }
            }
        }
    }
}
